From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56231) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y21NK-0004gs-M9 for qemu-devel@nongnu.org; Fri, 19 Dec 2014 12:30:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Y21NE-0007C6-NE for qemu-devel@nongnu.org; Fri, 19 Dec 2014 12:30:02 -0500 Sender: Paolo Bonzini Message-ID: <5494608F.4010307@redhat.com> Date: Fri, 19 Dec 2014 18:29:51 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <54915835.6030508@ilande.co.uk> <549159B6.6000006@suse.de> <54915F28.1090001@ilande.co.uk> <549164F5.5080902@suse.de> <5492DCAB.4050907@ilande.co.uk> <5492E8D6.3040503@suse.de> <549348E7.3020401@ilande.co.uk> <54935CE5.4090201@suse.de> <549403C2.8030902@ilande.co.uk> <54943249.2060902@ilande.co.uk> <54944F1E.7000604@ilande.co.uk> <54945779.9090103@ilande.co.uk> <54945D7E.3090409@suse.de> In-Reply-To: <54945D7E.3090409@suse.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Qemu-ppc] Unable to loadvm on qemu-system-ppc -M g3beige (keyboard freeze) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf , Mark Cave-Ayland , Peter Maydell Cc: "qemu-ppc@nongnu.org" , qemu-devel On 19/12/2014 18:16, Alexander Graf wrote: > > > On 19.12.14 17:51, Mark Cave-Ayland wrote: >> On 19/12/14 16:35, Peter Maydell wrote: >> >>> On 19 December 2014 at 16:15, Mark Cave-Ayland >>> wrote: >>>> It looks like after restoring the CPU state with loadvm env->htab_base >>>> is still at 0x0 rather than its pre-migration value of 0x7e000000. >>> >>> Odd -- there is code that is at least trying to do that: >>> machine.c calls ppc_store_sdr1() which should set htab_base/mask >>> according to the migrated value of the register... >> >> Stepping through ppc_store_sdr1() I see the problem is the if() statement: >> >> if (env->spr[SPR_SDR1] != value) { >> .... >> } >> >> It looks like env->spr[SPR_SDR1] has already been set to 0x7e000000 >> before the call to ppc_store_sdr1() and so as the values are already >> equal then the code to setup env->htab_mask and env->htab_base is bypassed. >> >> The quick fix is to comment out the above if() statement which allows me >> to restore my OpenBIOS image successfully with -loadvm but sadly not my >> OS image (I guess there are probably a few more state bugs still lying >> around). Does this seem the right thing to do or is there a better way? > > How about something like this instead? Then we at least don't lose the > acceleration we get from not invalidating the TLB on identical SDR1 writes. > > > Alex > > > diff --git a/target-ppc/machine.c b/target-ppc/machine.c > index c801b82..6f347bf 100644 > --- a/target-ppc/machine.c > +++ b/target-ppc/machine.c > @@ -71,6 +71,7 @@ static int cpu_load_old(QEMUFile *f, void *opaque, int > version_id) > for (i = 0; i < 1024; i++) > qemu_get_betls(f, &env->spr[i]); > if (!env->external_htab) { > + env->spr[SPR_SDR1] = 0; > ppc_store_sdr1(env, sdr1); > } > qemu_get_be32s(f, &env->vscr); Or even move the tlb_flush and if to the caller, helper_store_sdr1. It is only needed there, and would get in the way if one day PPC were to support --disable-tcg (which removes cputlb.c from the executable). Paolo